Variable area jet nozzle



R. E. WEILER ETAL VARIABLE AREA JET NOZZLE July 15, 1952 Filed sein. so, 1949 2I SHEETS-SHEET l INVENToRs ROBERT E. wElLER JAMES $.HAR0TGG awa@ ATTORNEY July l5, 1952 R. E. wl-:ILER ETAL VARIABLE AREA JET NOZZLE 2 Sl-IEETS--SHEET 2 Filed Sept. 30, 1949 .welLER s. HARDIGG @V2M ATTORNEY INVENTORSI- ROBERT E JAMES BY Patented July 15, 1952 folosii'ro lids which miglio involve siriioii'irzli` and ,-si'ill zooilieiobieei jfs-io provide ariadi'iisi; able nozzle siruoiure n"vii-moli vmay` be utilized lo .esizblislieither a conical nozzle, vloi Aii.-oioil'veifgirig*- viiiviiii'gin'g nozzle oxliibiiingfavorzblo 'chaiiz'oie'i ooi'i'imiinioaiion generally-- iiiziiooiodeo iafwliioii oxioiiiiz .loii-eiiudiioa-lliriliroiighfilieioiigiii,'from a-sfioiiozlzirmii-liofiiiri'oiy la fioz'. rearwardly-dia poseorlisoiiaiieognozzl is. #rho operating-ole: menig of iljioeiigiiiie foie` disposed in axial align; meilethezasingisiruoiiiroiano-inoliidoan through-theiniiimoz-asliafizo-wlliofi isi join-Y iioleii iii suiioloioea'riiligs --sinouiiiedi iin-*ille .cole 'structure "12. The geiioralipririoiplesoperation of-suoli--a poweplanearo wellililiowiifaml members havineloii'giiudinallydisposed lixible force.

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i bastion/off fuel supplied ille lo ,sifliifiiidwihin 'th section I ,esbeifsriqwh iiiFigs. 2 orjiii -f3iisoifrlisioooiiiozlinner: wall-oli .seeiioii 2 4;- ihefiieiizgriiosi: portion oi'wliiiolifdeflnes formed therein a plurality of equally spaced notches or slots 2Ia and 24a, which provide longitudinally disposed flexible leaves 21 on the outer section that overlap the slots between similar leaves 28 formed on the inner section (see Fig. 3). It will be understood that the inherent resiliency of the overlapped leaves 21 and 28 will tend to maintain them in a normal position, as shown in Fig. 2, forming substantially the preferred frusto-conical contour and annular flow area for the nozzle l5 as a whole. On the other hand, the leaves are suillciently flexible to respond to a radially inwardly directed or constricting force, and can thus be bent inwardly when it is desired to reduce the flow area of the nozzle, as hereinafter explained. It will be noted that the slots 2|a and 24a are longitudinally formed throughout a substantial extent of the outer and inner sections, respectively, providing leaves 21 and 28 preferablyexceeding one-half the axial length of the nozzle structure.

For effecting the desired degree of convergence of the cooperating flexible leaves 2,1 and 28, there is provided a flexible annular ferrule member or cable 33, which is disposed in encompassing engagement with the outer leaves 21, and which has its opposite end portions operatively supported on a pair of spaced pulleys 3 I. rThe pulleys 3l may be rotatably mounted on a suitablel stationary support, such as a rearwardly projecting hinged bracket 32 carried by the engine casing structure. In order that the cable 30 maybe restrained from displacement relative to the .canted leaves 21, L J-shaped elements or channels 33 are mounted on a number of the leaves, for receiving the cable.- Any suitable mechanism, indicated generally at 34 in Fig. 1, may be provided to'vary the tension force on the cable 36, so that the leaves 21 and 28 can be flexed inwardly and set in a relatively converging position, `for example, when it is desired to reduce the flow area of jet nozzle. By subsequently releasing the cable ,313., the leaves 21 and 28 will be permitted structure 46 supported from the casing Il.

tto expand or flex outwardly toward the normal position vshown in Fig. 2, in response tothe presasure of motive fluid vented through the nozzle during operation of the turbojet engine. Y Y

Referring to Figs. 6 and 1, the invention is therein disclosed in an alternative form, in which a' nozzle structure 35, preferably having somewhat greater axial length than the nozzle I5 already described, is provided vin association with two cables 36 and 31 for operation to effect variations in the axial conformation or flow pattern of the nozzle as'well as preselection of the flow area.

It has been'demonstrated that as the flight speed of a jet propelled aircraft is increased, the velocity of the jet issuing from the nozzle also rises and may enter the supersonic range. For nozzle exit velocities at a Mach number in excess of about 1.3, or when the vnozzle jet velocity is greater than about 1.3 times the jet acoustic velocity, a converging-diverging nozzle may exhibit more efficient operational characteristics than a simple converging nozzle. According to the invention, the nozzle 35 is constructed and arranged to render available either a variable area converging nozzle, illustrated in Fig. 6, or a variable area converging-diverging nozzle asv aeoaoea a plurality of outer flexible leaves 42 and over'- lapping inner leaves 43. For actuating the adjustable nozzle structure thus provided, the cable 36 is wrapped about the leaves 42 adjacent the discharge opening of the nozzle 35, and may be operatively engaged in suitable channels 44 carried by certain of the leaves. The cable 3'1 is similarly engaged in channels 44 and mounted in encompassing relation about the leaves 42 along a plane intermediate the cable 3S and the forward flanged end of the nozzle assembly. The ends of the rearmost cable 36 may be passed over suitable pulleys 45 mounted on a hinged carrier In like manner, the ends of the cable 31 are adapted toengage pulleys 41 that are mounted on a suitable stationary carrier structure 48.

It will be understood that each of the cables 36 and 31 is arranged for application of any desired tensioning force on the associated flexible leaves of the nozzle assembly, as hereinbefore explained in connection with the cable 3U shown in Fig. 1. Thus, if it is desired to effect a reduction in the flow area of the nozzle 35, without departing from the generally frusto-conical form shown in Fig. 6, both cables will be tightened simultaneously to maintain the desired relationship. If it is desired to effect a change in the form of the nozzle to the converging-diverging shape illustrated in Fig. 8 for use at supersonic velocities, the intermediate cable 31 will be actuated to force inwardly the central portions of the flexible leaves 42 and 43 while the end cable 36 may be released to a limited extent for permitting. ex.- haust gas pressure to expand the outerend of the nozzle assembly,

The terminal ends of the outer leaves 42 may, as shown in Fig. 8, be curved outwardly to afford adequate stiffness to the thin stock from which the nozzle sections are made, and to ensure maintenance of the circular nozzle exit opening.

From the foregoing, it will be apparent that a nozzle structure constructed and arranged in accordance with the invention may be built from materialof relatively light weight, and will be readily operative to effect variations in nozzle form and flow area, in increments small enough to facilitate accurate adjustment thereof promoting optimum engine performance under most service conditions. The basically conical shape of the improved nozzle, symmetric in cross section, renders the assembly readily useful in association with either engine equipment of existing form ;or power plants of advanced design.

` While the invention has been shown in several forms, it Will be obvious to those skilled in the-art that it is not so limited, but is susceptible of various other changes and modifications without departing from the spirit thereof.

What is claimed is:

1-.Motive fluid discharge nozzle apparatus comprising substantially cylindrical casing 'structureterminating in double frusto-conical retractile wall sections forming a nozzle opening, both of said wall sections having staggered axial slits formed therein through more than half the longitudinal extent of said wall sections for providing a plurality of overlapping flexible elongated leaves, a, rst retractile cable 'operatively looped about said leaves at an annulus intermediate the ends of said wall sections, and a secondretractile cable operatively looped about said leaves adjacent Athe free ends thereof, said cables beingiindependently operative tavary the flow areaan the axial-conformation ofysaid nozzlefmti; 't j..

2. Motive iiuid discharge nozzle apparatus comprising substantially cylindrical casing structure terminating in double frusto-conical retractile wall sections forming a nozzle opening, both of said Wall sections having staggered axial slits formed therein through more than half the longi.. tudinal extent of said Wall sections for providing a plurality of overlapping ilexible elongated leaves, a, rst retractile cable operatively looped about said leaves at an annulus intermediate the ends of said Wall sections, and a second retractile cable operatively looped about said leaves adjacent the free ends thereof, said first cable being operative at will to force radially inwardly the central portion of said leaves while said second cable is operated to effect relative outward movement of the free ends thereof underthe pressure of discharging motive fluid, for thereby providing a converging-diverging nozzle passage.

ROBERT E. WEILER. JAMES S. HARDIGG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

